Welcome Gina!
Welcome to ATP and to gardening.
I don't have exdperie4nce gardening in an arid area, but I did learn one thing about raised beds. (Or, at least, raised beds with porous walls and some gaps.)
They dry out pretty fast, especially in the corners and around the edges!
I use concrete paving stones 3/4" thick, or 1" thick. There are always gaps in the corners, and the soil in the corners dries out much sooner than the rest of the bed.
So now I make a habit of saving the heavy plastic from bags or bales or potting soil, bark mulch and other soil amendments. I cut them open so they are single-thickness, heavy plastic film.
Then I cut them to a width that lets me line my raised bed walls with plastic film. That keeps the edges - and most especially the corners - from drying out by evaporating right through the walls.
It looks better if the plastic doesn't stick up above soil level. It is easiest to install the plastic before filling the bed with soil. But you can also shovel soil away from a few feet of wall, tuck the plastic into place, and then shovel away from the next few feet (throwing soil into the center of the bed temporarily).
Sometimes I let the lower edge of the plastic fold over and lay flat on the "floor" of the raised bed (the compacted clay floor UNDER the amended soil). If you have sandy subsoil, that would provide a narrow strip where water would not drain down rapidly into dry subsoil.
Once I was forced to line the entire bottom of a narrow raised bed with plastic. I didn't want to, but roots from heather and bushes would otherwise have invaded that bed right away. Well, I lucked out and now that bed is my only bed that stays moist for a long time with minimal watering. Because of the plastic under it and around the walls, it acts like a very big planter instead of a very small raised bed! It still drains after a rain becuase of small gaps in the plastic, but the underlying soil and roots do not suck water out of the bed as fast as I add it.
That may be helpful to you, if your water is expensive and subsoil drains rapidly.
P.S. Another way to conserve water and keep soil moist and cool is to always add coarse mulch as a top layer. Around 2 inches of wood chips or bark chunks or other mulch will slow down evaporation, and prevent the sun and watering from beating directly onto the soil.
If you ever put hoops on your beds so you can keep them warm through the winter with plastic film, leave the hoops in place during the summer and use well-ventilated shade cloth instead of plastic! The ssmae hoops can keep it warm in the winter, and less hot in the summer. By diverting some of the wind, it might also slow down evaporation.
